Am a bit of an adrenaline junkie and have 2 GoPros that I use to create movies with in iMovie. At the moment I can't seem to make any as my startup disk is full of 575 gb of Movie data, despite transferring all of the videos out of iPhoto and movies out of iTunes and iMovie and from various other locations. I have also deleted previous iMovie events to free up some data but only 10Gb. Anyone have any idea what I can do without having to restore my mac? Its almost like theres a fault and its storing data that isn't actually there. Cheers!
When you delete something in iPhoto it goes to iPhoto's trash. Then from there it goes to the OS X trash. So you need to empty both of those trashes to reclaim the drive space.
Also, I use DaisyDisk to see where I have the most space being taken up. They have a free trial, but you will find it invaluable for freeing up drive space.
Something I use to move videos from iPhoto to external storage is the iPhoto Manager. It will copy the actual event from iPhoto do a different iPhoto library. In my case I have different libraries on different external drives. So I sync everything to the library on my internal drive. From there I can edit, share, etc. Then later I hook up the external drives and copy the events to the correct drives, then delete them from the internal library.